DLPDLCR471TPEVM: Low contrast or excessive stray light in off state

Olov von Hofsten

Part Number: DLPDLCR471TPEVM

Tool/software:

I am measuring checkerboard contrast with the EVM and I get values around 1:75. Is this normal? The off-state light is also considerably higher than cropped pixel values (flat-state?). Why is this? And is it possible to get the blackness values of the cropped pixels to the black pixels? See attached image. The top part is black, the lower part is cropped. Is there some setting to reduce the blackness values?

5 months ago

0 Lori Wang 5 months ago

TI__Genius 11565 points

Hi User,

How do you set your checkboard in TPG? I may don't understand your question, can you please describe the steps you performed on the EVM?

Regards,

Lori

0 Olov von Hofsten 5 months ago in reply to Lori Wang

Prodigy 20 points

Hi Lori, I set the checkerboard via windows. I discovered now that this is due to image processing settings. Image processing is not applied to cropped pixels. If i turn off gamma bit, the black level is reduced. White levels are also reduced but can be increased by higher brightness levels. This does however bring the black level up again... What are the best image processing levels to maximise checkerboard contrast?

0 Lori Wang 5 months ago in reply to Olov von Hofsten

TI__Genius 11565 points

Hello User,

Thank you for confirmed that you figured out the black level. If you using external HDMI display mode, then you should be able to change/modify your displayed pattern by yourself. I'm not sure if that is the checkerboard contrast you are mentioning.

Regards,

Lori

0 Olov von Hofsten 5 months ago in reply to Lori Wang

Prodigy 20 points

Yes, that is correct. I am using a HDMI cable to display a checkerboard pattern. I am still not getting optimum contrast, because I do not understand the image processing settings. Is there any documentation on how the gamma curves work, or "contrast setting" or "brightness"? These settings do not work as expected in all cases.

+1 Lori Wang 5 months ago in reply to Olov von Hofsten

TI__Genius 11565 points

Hello,

Please refer to DLPC6540 software programmer's guide, section 12 describe the image processing, and you can see these commands describe in the guide.

I hope this helps.

Regards,

Lori

0 Olov von Hofsten 5 months ago in reply to Lori Wang

Prodigy 20 points

Thank you, this partially solved my issues. For future questions on this subject, I found that the bestr contrast performance was achieved with gamma turned off and brightness set to 10.

0 Lori Wang 5 months ago in reply to Olov von Hofsten

TI__Genius 11565 points

Thank you for providing the update.

Regards,

Lori

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DLPDLCR471TPEVM: Low contrast or excessive stray light in off state